Jaw closure detection system

ABSTRACT

A jaw angle detection system for an end effector assembly includes a first electrical contact that connects to a first jaw member and connects to a generator. A sensor connects to a second jaw member (or an actuator) and connects to the generator, and configured to move relative to the first electrical contact upon movement of the second jaw member (or the actuator) when the first and second jaw members are moved to close about tissue disposed therebetween. Information relating to the position of the sensor relative to the first electrical contact is relayed back to the generator to determine an angle between the first and second jaw members.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 13/736,650, filed on Jan. 8, 2013, which is adivisional application of U.S. patent application Ser. No. 12/419,735,filed on Apr. 7, 2009, now U.S. Pat. No. 8,357,158, which claims thebenefit of and priority to U.S. Provisional Patent Application Ser. No.61/046,882, filed on Apr. 22, 2008, the entire contents of each of whichbeing incorporated by reference herein.

BACKGROUND

The present disclosure relates to a jaw closure detection system forperforming electrosurgical procedures. More particularly, the presentdisclosure relates to a jaw sensing system that detects and/or confirmsjaw closure about tissue and/or detects the relative angle of twoopposing jaw members relative to one another when tissue is engagedtherebetween.

TECHNICAL FIELD

Forceps utilize mechanical action to constrict, grasp, dissect and/orclamp tissue. Electrosurgical forceps utilize both mechanical clampingaction and electrical energy to effect hemostasis by heating the tissueand blood vessels. By controlling the intensity, frequency and durationof the electrosurgical energy applied through the jaw members to thetissue, the surgeon can coagulate, cauterize and/or seal tissue.

In order to effect a proper seal with larger vessels or thick tissue,two predominant mechanical parameters must be accurately controlled: thepressure applied to the tissue; and the gap distance between theelectrodes. As can be appreciated, both of these parameters are affectedby the thickness of vessels or tissue. More particularly, accurateapplication of pressure is important for several reasons: to reduce thetissue impedance to a low enough value that allows enoughelectrosurgical energy through the tissue; to overcome the forces ofexpansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal.

In some instances, in order to properly and effectively seal largervessels or tissue, a greater closure force between opposing jaw membersis required and accurate detection of jaw closure and in some cases thejaw closure angle is important to assure a consistent and reliable seal.This presents a design challenge for manufacturers because the jawmembers are typically affixed with pins which are positioned to havesmall moment arms with respect to the pivot of each jaw member and it isoften difficult to assess accurate jaw closure. Further, many of theseknown instruments generally rely on clamping pressure alone to procureproper sealing thickness and are often not designed to take into accountjaw closure variables relating to gap tolerances and/or parallelism andflatness requirements which are parameters which, if properlycontrolled, can assure a consistent and effective tissue seal.Confirmation that the jaw members are both closed about tissue andoriented at a correct angle are important factors which, when properlycontrolled, assure a consistent and reliable tissue seal.

SUMMARY

The present disclosure relates to a jaw closure mechanism or jaw angledetector for an end effector assembly of a forceps and includes a firstelectrical contact that connects to a first jaw member and connects to agenerator (or a controller). A sensor is included that connects to asecond jaw member (or an actuator) and connects to thegenerator/controller. The sensor is configured to move relative to thefirst electrical contact upon movement of the second jaw member (or theactuator) when the first and second jaw members are moved to close abouttissue disposed therebetween. Information relating to the position ofthe sensor relative to the first electrical contact is relayed back tothe generator/controller to determine an angle between the first andsecond jaw members. This information is conveyed to the user by amonitor or other type of visual or audible indicator. The relativeposition of the first electrical contact relative to the sensor may berepresented in binary code.

In embodiments, the sensor includes a variable resistor, a series ofresistors or a voltage divider network (potentiometer) that relaysinformation back to the generator (or controller). In yet anotherembodiment, the sensor includes a variable capacitor that may includefirst and second conductive rings, the first conductive ring being fixedrelative to the second conductive ring.

In another embodiment, the sensor includes a second electrical contactthat is positioned to conduct a signal back to the generator/controllerwhen the second electrical contact electrically connects to the firstelectrically contact upon the jaw members closing about tissue past aparticular angle, e.g., a threshold angle. The threshold angle being anangle wherein the jaw members are closed about tissue to assure aconsistent and reliable seal.

The present disclosure also relates to a jaw angle detector having firstand second jaw members and first and second conductors (e.g., conductiverings) adapted to connect to a capacitive sensing circuit of anelectrical generator. The first conductor is fixed relative to thesecond conductor and the second conductor is moveable relative to thefirst conductor upon movement of the jaw members from a first spacedposition relative to one another to a second position closer to oneanother. Information relating to the position of the second conductorrelative to the first conductor is relayed back to the capacitivesensing circuit to determine an angle between the first and second jawmembers. In embodiments, the second conductor is attached to a drive rodof an endoscopic electrosurgical forceps or a movable jaw member of aunilateral endoscopic electrosurgical forceps.

The present disclosure also relates to a jaw angle detector thatincludes first and second jaw members each having proximally extendingflanges adapted to connect to an electrosurgical energy source forconducting energy through tissue held between jaw members. A conductoris disposed on the proximal flange of the first jaw member and avariable resistor (e.g., series of resistors, voltage divider network,etc.) is disposed on the proximal flange of the second jaw member inopposing relation to the conductor. The first conductor and the variableresistor are adapted to relay a signal to a sensing circuit of theelectrosurgical generator. The movement of the jaw members from an openspaced apart position to a closed position causes the conductor to moveacross the variable resistor and vary the signal relayed back to thesensing circuit, which, in turn, determines an angle between the firstand second jaw members. In embodiments, the variable resistor isdisposed in a port defined in the second jaw member, the port beingconfigured to mechanically receive the conductor therein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described herein withreference to the drawings wherein:

FIG. 1A is a side view of unilateral laparoscopic bipolar forcepsconfigured to support one embodiment of a jaw closure detection systemaccording to the present disclosure;

FIG. 1B is an enlarged, side view of an end effector assembly of an openbipolar forceps configured to support another embodiment of a jawclosure detection system according to the present disclosure;

FIG. 2 is an enlarged, side view of an end effector assembly of an openbipolar forceps configured to support one embodiment of a jaw closuredetection system according to the present disclosure;

FIG. 3 is a side view of a bilateral endoscopic bipolar forcepsconfigured to support another embodiment of a jaw closure detectionsystem according to the present disclosure including a variableresistor;

FIG. 4A is a front, perspective view of an end effector assembly of anopen forceps showing a jaw closure detection system in a firstorientation prior to grasping tissue;

FIG. 4B is a front, perspective view of the end effector assembly ofFIG. 4A showing the jaw closure detection system in a second orientationwith the jaw members closed;

FIG. 5 is a schematic view of a drive actuator of an endoscopic forcepsconfigured to support another embodiment of a jaw closure detectionsystem according to the present disclosure including a variablecapacitor; and

FIG. 6 is a schematic circuit diagram of a capacitive sensing circuitfor use with the variable capacitor of FIG. 5.

DETAILED DESCRIPTION

Referring to FIGS. 1A-6, various embodiments of a jaw closure detectoror sensing mechanism are disclosed in accordance with the presentdisclosure. A laparoscopic, an endoscopic, or an open instrument may beutilized for supporting the jaw closure detector assembly; however,different electrical and mechanical connections and considerations applyto each particular type of instrument. In the drawings and in thedescription that follows, the term “proximal”, as is traditional, willrefer to the end of the forceps that is closer to the user, while theterm “distal” will refer to the end of the forceps that is further fromthe user.

FIG. 1A shows a unilateral laparoscopic vessel sealing forceps 10 thatis configured to support an electrode sealing assembly 100. Forceps 10typically includes various conventional features (e.g., housing, ahandle assembly, a rotating assembly, a trigger assembly (all notshown)) that enable the forceps 10 and the end effector assembly 100 tomutually cooperate to grasp, seal and, if warranted, divide tissue. Theforceps 10 includes a shaft 12 that has a distal end 14 dimensioned tomechanically engage the end effector assembly 100 and a proximal end(not shown) that mechanically engages the housing (not shown). Detailsrelating to the inter-cooperative relationships of the variouscomponents of forceps 10 are disclosed in commonly-owned U.S. Pat. No.7,150,749, the entire contents of which is incorporated by referenceherein.

Forceps 10 also includes a plug (not shown) that connects the forceps 10to a source of electrosurgical energy, e.g., an electrosurgicalgenerator 501, via one or more electrical cables (not shown). Otherelectrical connections (not shown) are positioned through the shaft 12and end effector assembly 100 to supply bipolar electrical energy toopposing sealing surfaces 112 and 122 of jaw members 110 and 120,respectively. The jaw members 110 and 120 move in response to movementof an actuator or handle (not shown) from an open position wherein theelectrically conductive sealing surfaces 112 and 122 are disposed inspaced relation relative to one another, to a clamping or closedposition wherein the electrically conductive sealing surfaces 112 and122 cooperate to grasp tissue 401 (See FIG. 2) therebetween. Again,details relating to the inter-cooperative relationships of theinner-working components of the actuator or handle of the forceps 10 aredisclosed in commonly-owned U.S. Pat. No. 7,150,749, incorporated byreference above. When the electrically conductive sealing surfaces 112and 122 of the jaw members 110 and 120 are fully compressed about thetissue, the forceps 10 is now ready for selective application ofelectrosurgical energy.

As mentioned above, FIG. 1A shows a bipolar forceps 10 that includes aunilateral end effector assembly 100 having one stationary or fixed jawmember 120 mounted in fixed relation to the shaft 12 and pivoting jawmember 110 mounted about a pivot pin 103 attached to the stationary jawmember 120. A reciprocating sleeve 60 is slidingly disposed within theshaft 12 and is remotely operable by the drive actuator (not shown). Thepivoting jaw member 110 includes a detent or protrusion 125 that extendsfrom jaw member 110 through an aperture defined within the reciprocatingsleeve 60. The pivoting jaw member 110 is actuated by sliding the sleeve60 axially within the shaft 12 such that a distal end of the apertureabuts against the detent 125 on the pivoting jaw member 110. Pulling thesleeve 60 proximally closes the jaw members 110 and 120 about tissuegrasped therebetween and pushing the sleeve 60 distally opens the jawmembers 110 and 120 for grasping purposes.

In one embodiment, one of the jaw members, e.g., jaw members 110,includes a sensor 30 disposed on detent 125. Reciprocating sleeve 60includes one or more corresponding sensors 40 a-40 c disposed on adistal end 61 thereof. The sensors 30 and 40 a-40 c are electricallycoupled to a feedback circuit associated with the generator 501 or anindependent controller 502 via leads 75 b and 75 a, respectively, whichdetermines the position of sensor 30 relative to sensors 40 a-40 c,respectively, and associates the relative position with a jaw angle “α”between jaw members 110 and 120. The sensors 30 and 40 a-40 c may bemagnetic, resistive, capacitive, optical or any other suitable type ofsensor. In use, as the user actuates the drive sleeve 60 proximally toclose the jaw members 110 and 120 relative to one another, sensor 30, inturn, moves relative to sensors 40 c-40 a. The feedback loop calculatesthe angle “α” of the jaw members 110 and 120 and provides theinformation back to the user.

The sensors 30 and 40 a-40 c may also be configured to provideadditional feedback to the user relating to tissue thickness (based onrelative resistance to closure), speed of jaw closure and if the jawmembers 110 and 120 are closed appropriately about tissue forapplication of electrosurgical energy. Moreover, jaw closure angle “α”may be used to determine a “re-grasp” condition during sealing due toinsufficient jaw closure or may be used to determine the overalladequacy of the seal either prior to, during, or after activation. Inanother embodiment, the jaw closure angle “α” may be used modify theenergy delivery from the generator 501 to enhance the sealing process.

In another embodiment, a single electrical contact 240 may act as asensor to determine jaw closure and provide information to the generator501 regarding the jaw angle “α”. For example, FIG. 2 shows anotherforceps design 200 that includes two opposing jaw members 210 and 220movable relative to one another about a pivot 265 to engage tissue. Jawmembers 210 and 220 each include an electrically conductive surface 212and 222, respectively, disposed thereon that connects to generator 501for selectively conducting bipolar energy through tissue.

Jaw member 220 also includes a proximal portion or base 245 having guideslot 224 defined therein that allows a terminal connector 250 orso-called “POGO” pin to ride therein upon movement of the jaw members210 and 220 from the open to closed positions. A corresponding base 235of jaw member 210 includes a sensor or contact 240 disposed proximateslot 224 that electrically connects to the generator 501 or independentcontroller 502. As explained above, the sensor 240 may be configured toprovide information back to the generator via one or more feedback loopsrelating to the angle “α” of the jaw members 210 and 220 relative to oneanother.

Sensor 240 may also be configured to provide additional information backto the generator 501 as explained above. In one embodiment, the sensor240 may act as a safety mechanism wherein the electrical contact 240simply determines if the two opposing jaw members 210 and 220 are movedclose enough together (e.g., have moved past a threshold angle) forapplication of electrical energy. In this manner, when the jaw members210 and 220 are closed to an angle less than desired or less thanappropriate to commence sealing, the sensor 240 does not electricallyconnect to terminal connector 250 to send a signal back to the generator501 to allow activation. For example, when the jaw members 210 and 220are opened at an angle not appropriate to seal vessels or tissue, thesensor 240 may be positioned opposite (or relative to) a non-conductivematerial and, as a result, does not conduct a signal back to thegenerator 501. Conversely, when the jaw members 210 and 220 are closedpast a threshold angle, the sensor 240 is positioned opposite (orrelative to) terminal connector 250 and conducts a signal back togenerator 501 to allow activation.

In some embodiments, a series of sensors e.g., sensors 140 a and 140 b,may be employed along or on a distal end of drive sleeve 160 such thatthe relative angle “α” between the jaw members 110 and 120 may bedivided into discreet units for finer resolution (See FIG. 1B). Forexample, in the instance where two sensors 140 a and 140 b are utilizedto determine the relative angle between jaw members 110 and 120,information relating to the state of conductivity of each electricalconnection between the respective sensors 140 a and 140 b and connector130 can be communicated back to the generator 501 via leads 133, 143 aand 143 b, respectively, in binary format, e.g., “00” (no contact witheither sensor 143 a or 143 b); “01” (contact with first sensor 143 a);“11” (contact with both sensors 143 a and 143 b); and “10” (contact withsecond sensor 143 b).

FIG. 3 shows yet another forceps 300 that utilizes a variable resistor340, e.g., a voltage divider network (“VDN”), to determine jaw angle“α”. VDN 340 may be a film-type potentiometer that forms a switchclosure. For the purposes herein, the term “voltage divider network”relates to any suitable form of resistive, capacitive or inductiveswitch closure (or the like) that determines the output voltage across avoltage source (e.g., one of two impedances) connected in series. A“voltage divider” as used herein relates to a number of resistorsconnected in series that are provided with taps at certain points tomake available a fixed or variable fraction of the applied voltage.

In this instance, actuating pin 330 would act as a contact across theVDN 340 such that, as the actuating pin 330 is translated within a slot345 within shaft 312 and respective cam slots 374 and 372 in jaw members310 and 320, the actuating pin 330 would move relative to the VDN 340,thereby varying the intensity of the signal relayed back to thegenerator 501 which, in turn, may be utilized to determine jaw angle“α”. Additional wiring (not shown) may be required to accomplish thispurpose, but a finer resolution of jaw angle “α” may be determined.

FIGS. 4A and 4B show another embodiment of an open forceps 400 having asimilar style sensor arrangement for determining jaw angle “α”. Moreparticularly, forceps 400 includes two opposing jaw members 410 and 420that are movable relative to one another about a pivot 450. Each jawmember 410 and 420 includes a flange 442 and 432 that extends proximallytherefrom. Flange 432 includes a contact 440 that is mechanicallyreceived within a complementary interface 431 disposed on flange 442that houses VDN 430. During movement of the jaw members 410 and 420 fromthe open position to the closed position, contact 440 moves from aspaced position relative to interface 431 (as shown in FIG. 4A) to aseries of subsequent positions within interface 431 as the contact 440moves across the VDN (or series of resistors), thereby varying theintensity of the signal relayed back to the generator 501 fordetermining jaw angle “α”.

FIG. 5 shows another embodiment of a forceps 500 wherein a driveactuator 560 has been modified to include a variable capacitor 520 todetermine the jaw angle “α” between two opposing jaw members, e.g., jawmembers 110 and 120. More particularly, variable capacitor 520 includesa fixed conductor, e.g., a conductive ring 540 disposed on a forcepshousing (not shown) or jaw member 110 and 120 that encapsulates a secondconductor, e.g., a conductive ring 530, disposed on the drive actuator560. Movement of the drive actuator 560 moves the conductive ring 530relative to the conductive ring 540. A dielectric insulator (not shown)may be placed between the two rings 530 and 540 (e.g., air or insulatinglubricant).

As the drive actuator 560 moves to close the jaw members 110 and 120,the conductive rings 530 move relative to the fixed conductive ring 540thereby changing the capacitance between the two conductive rings 530and 540 based on a capacitive sensing circuit 600 described below withrespect to FIG. 6. The change in capacitance can be detected andtransmitted to the generator 501 or controller 502 to determine the jawclosure angle “α” between the two jaw members 110 and 120. In oneembodiment, the conductive rings 530 and 540 may both be movablerelative to one another to accomplish a similar purpose.

FIG. 6 shows one example of a variable capacitance circuit 600 for usewith the embodiment described with respect to FIG. 5. As mentionedabove, the conductive rings 540 and 530 form a variable capacitor 520that transmits a signal back to the generator 501 and circuit 600. Theconnection of the variable capacitor 520 to the voltage source (labeled+5v) causes the variable capacitor 520 to charge when S2 is open, S3 isopen and S1 is shut. After a predetermined amount of time, S1 opens andS2 shuts. This causes the charge stored on the variable capacitor 520 tobe transferred to the charge capacitor 620. S2 then opens and theprocess is repeated for a predetermined number of cycles. The resultingvoltage on the charge capacitor 620 can then be read (in this case by ananalog to digital converter 630). S3 is then closed and re-opened todischarge the charge capacitor 620. The entire cycle is then repeated ata desired read rate. The read voltage is proportional to the capacitanceof the variable capacitor 520 which, in turn, relates to the jaw angle“α” between jaw members, e.g., jaw members 110 and 120.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, one or more stop members may be disposedadjacent to or disposed on one or both electrically conductive sealingsurfaces of the jaw members to regulate the gap distance betweenconductive surfaces, The distance the stop members extend from theelectrically conductive surfaces may effect the jaw angle “α” betweenjaw members. The generator may have to be programmed (automatically ormanually) to account for this feature when determining the overall jawangle “α” and any type of threshold angle as mentioned above. Moreover,the tissue thickness may also effect the jaw angle “α”. Again thegenerator may have to be programmed (automatically or manually) tocompensate for these various tissue types.

One or more of the jaw closure detectors described herein may beconfigured to detect the change in the jaw closure angle “α” over aperiod of time during the sealing process. This information may also berelayed back to the generator for determining seal quality and overallsuccess of the resulting seal.

In some embodiments, any of jaw closure detectors described herein maybe coupled to a controller 502 that is electrically coupled to thegenerator 501 or, in some instances, independent from the generator 501.The controller 501 (if independent) may be configured to provide any orall of the features described herein with respect generator 501.

While several embodiments of the disclosure have been shown in thedrawings and/or discussed herein, it is not intended that the disclosurebe limited thereto, as it is intended that the disclosure be as broad inscope as the art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

What is claimed is:
 1. A jaw angle detection system, comprising: firstand second jaw members each having a flange extending proximallytherefrom, the first and second jaw members configured to connect to anelectrosurgical energy source for conducting energy through tissue heldbetween the first and second jaw members, the flange of the second jawmember defining an interface therein; a contact disposed on the flangeof the first jaw member; and a variable resistor disposed in theinterface of the flange of the second jaw member in opposing relation tothe contact, the contact and the variable resistor adapted to relay asignal to a sensing circuit of an electrosurgical energy source, whereinmovement of the first and second jaw members from an open position to aclosed position causes the contact to be received within the interfacedefined in the flange of the second jaw member and move across thevariable resistor to vary the signal relayed back to a sensing circuitto determine an angle between the first and second jaw members.
 2. Thejaw angle detection system according to claim 1, wherein the first andsecond jaw members are configured for use with an open electrosurgicalforceps.
 3. The jaw angle detection system according to claim 1, whereinthe variable resistor includes a series of resistors.
 4. The jaw angledetection system according to claim 1, wherein the variable resistorincludes a voltage divider network.
 5. The jaw angle detection systemaccording to claim 1, wherein the contact projects from the flange ofthe first jaw member.
 6. The jaw angle detection system according toclaim 1, wherein the contact is disposed outside of the interface whenthe first and second jaw members are in the open position, and thecontact is disposed within the interface when the first and second jawmembers are in the closed position.
 7. The jaw angle detection systemaccording to claim 1, wherein the interface is recessed.
 8. The jawangle detection system according to claim 1, wherein the interface is achannel configured for receipt of the contact.